Blizzard's Titan: what we can learn from the latest WoW patch?

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Adam Oxford at

wow bandwidth

A relatively small technical issue for Blizzard’s Warcraft servers on Sunday night and a couple of innocuous Blue posts might well signal that the company’s next MMO - codenamed Titan and confirmed back in December - is going to be FPS-based. What sort of convoluted logic do we arrive at for that reasoning? You may well ask...

If you’ve looked at your World of Warcraft latency report since patch 4.0.6 went live last week, you may have noticed that what was once a single large number - often over 200ms on a decent connection - has been divided up into two smaller numbers called Home and World, which are 32ms and 178ms respectively on my current machine.

Many people - including me - initially assumed that the former, lower number was something to do with their LAN. Turns out we were wrong, and in a post picked up by MMO Champion’s Blue Tracker, Blizzard representative Brianl did an excellent job of explaining what was going on:

In essence, 'Home' refers to your connection to your realm server. This connection sends chat data, auction house stuff, guild chat and info, some addon data, and various other data. It is a pretty slim connection in terms of bandwidth requirements.

'World' is a reference to the connection to our servers that transmits all the other data... combat, data from the people around you (specs, gear, enchants, etc.), NPCs, mobs, casting, professions, etc. Going into a highly populated zone (like a capital city) will drastically increase the amount of data being sent over this connection and will raise the reported latency.

So far so straightforward, and Brianl went to describe how the difference between the two figures can be used to diagnose connection problems.

If your 'Home' connection latency is low and your 'World' connection latency is high, that frequently indicates that there is some sort of QoS congestion controls being applied to your internet connection, at either the micro (LAN) or macro (WAN) level. A common symptom would be that you would be able to chat, but not to cast.

The most interesting part of the discussion, though, is a few posts later. Brianl revealed that around the same time as the patch, Blizzard had also made some changes to the way the ‘World’ servers for instances, raids, arena and battlegrounds handle network traffic. The changes were designed to lower client latency, but because the changes resulted in higher pings for less than 2% of players they hit CTRL-Z and reverted to the old system on Sunday night.

The problem, according to Brianl, was that reducing the ping times means increasing the number of times a game client talks to the server per second. On slower connections, or where ISPs deploy traffic shaping policies to throttle heavy users, the increase in packets sent to and from the servers was enough to flood the available bandwidth and cause substantially higher latency, making the game unplayable.

So far, so much kudos to Blizzard for trying something new and then fixing an unforeseen problem pretty quickly. Also, to Brianl for bothering to explain something fairly esoteric for a lot of players.

But here’s where we get licence to indulge in some rampant speculation. Traditionally, the MMO client/server server relationship has been planned with high average latencies in mind in order to manage the vast quantity of information coming in from thousands of players at once - and the actual lag is disguised by game design which doesn’t require perfect synchronisation between the two. That’s why WoW and Eve et al aren’t ‘twitch’ games: a 16 player FPS server running a relatively tight map can afford to update each client in near real-time without using much in the way of bandwidth. For MMOs, there’s a literal ton of data in each update with player positions, NPC movements, item caches and so on.

Even in instances, there must be a point - probably higher than the 12ms Brianl claims he was getting over the weekend - where lower pings won’t actually have any noticeable effect on the gameplay.

Thus we can reasonably surmise that playing around with the underlying network structure isn’t necessarily to benefit current WoW players, but to test a new architecture for the next game - Titan - and that it needs FPS-style response times. QED.

Or they could just be trying to make WoW better, of course.

More seriously, though, it does raise highlight an issue about how technically viable a large scale MMO with all the rich detail of WoW but the fast pace of - say - PlanetSide - is. The WoW problems were caused by two things: invisible traffic shaping by ISPs and wireless connections including 3G and WiFi not being up to the task. It's one thing for Blizzard, which now makes up a significant part of all internet traffic, to experiment with low latency gaming and be able to move from one network management system to another smoothly and quickly to avoid complaints. But for an MMO of the future which is more reliant on low pings and whose parent company isn't as well resourced, and is fighting against more traffic shaping in the non-neutral net, it's going to be a massive issue to overcome.